1. Field of the Invention
The present invention relates to a power tool having a power transmitting mechanism for transmitting power of a driving motor to a tool bit.
2. Description of the Related Art
Japanese laid-open patent publication No. 1993-253854 discloses a screw tightening machine for tightening screws. A power transmitting mechanism of this screw tightening machine has a driving-side member rotationally driven by a driving motor and a driven-side member connected to a tool bit, and transmits power of the driving motor to the tool bit when the driving-side and driven-side members engage with each other via a claw clutch.
In the known screw tightening machine, when the driving-side and driven-side members are engaged with each other via the claw clutch, clutch teeth repeatedly hit each other. Therefore, wear of the clutch teeth may be accelerated so that the product life is shortened.
Therefore, in designing a power tool of this type including a screw tightening machine, an effective technique for preventing wear of a power transmitting part between a driving motor and a tool bit is required.